The purpose of this study is to delineate the sulfate donor specificity of 3'-phosphoadenylyl sulfate (PAPS) in the sulfoconjugation of both steroids and N-arylhydroxamic acids by the requisite sulfotransferase(s). To this end, it is planned to prepare a series of analogs of PAPS containing modifications in the adenine ring, in the sugar, and in the sulfatophosphate chain. The suitability of these analogs to function as sulfate donors will be examined by measuring the apparent Km and Vmax values for each of the compounds with the appropriate enzyme and acceptor. A comparison of the effect of structural alteration on the binding and catalytic activity of the analogs is expected to provide the basis for the design of reversible and active-site directed, irreversible inhibitors of sulfoconjugation of steroids and arylhydroxamic acids.